1. Field of Invention
The present invention relates generally to golf clubs and, more particularly, to composite resin/fiber golf club shafts.
2. Description of the Related Art
Many substitutes have been introduced for the hard wood shafts originally used in golf club drivers and irons. Early substitute materials included stainless steel and aluminum. More recently, carbon fiber reinforced resin shafts have become popular. Such shafts are typically hollow and consist of a shaft wall formed around a tapered mandrel. The use of fiber reinforced resin has allowed golf club manufacturers to produce shafts having varying degrees of strength, flexibility and torsional stiffness. As such, manufacturers are able to produce shafts which suit the needs of a wide variety of golfers.
Nevertheless, manufactures are faced with a variety of design issues that have proven difficult to overcome using conventional fiber reinforced resin technologies. For example, some golfers prefer that the center of gravity of the shaft be shifted towards the tip of the shaft in order to increase the striking force when the club head impacts the golf ball. This can be difficult to accomplish with conventional technologies because composite materials are generally light. It is also preferable in some instances to increase the kick of the shaft. One conventional method of increasing the kick of a shaft is to use a large number of graphite fibers that have a very high modulous of elasticity. This method is, however, very expensive. Another method is to alter the shape of the shaft, as is disclosed in commonly assigned U.S. Pat. No. 5,957,783. Another design issue is the location of the shaft flex point and, more specifically, the inability of shaft designers to precisely predict the location of the flex point when designing a shaft without using excessive amounts of composite material, which can lead to weight and thickness issues.